Sweet sorghum: from booze to biofuel

During World War II, when sugar was rationed, bootleggers used the juice of sweet sorghum to make moonshine. Now researchers at the University of Missouri Delta Research Center are studying ways to boost the plant’s potential to brew not booze, but biofuel.

The corn-like grass, which can grow to 12 feet, already shows promise as a source of ethanol, said Gene Stevens, MU Extension agronomist at the Delta Center, Portageville, Mo., in the Missouri Bootheel. It can yield as much ethanol as corn with less nitrogen and water; returns nutrients to the soil; and uses less energy in the ethanol production process.

However, the plant, which is native to Africa, is best adapted to warmer climates and has a shorter growing season in Missouri and other temperate regions, which lowers its ethanol — and profit — potential.

At the Delta Center, Stevens and MU graduate student Roland Holou are studying cold-tolerance in sweet sorghum as a way to boost the plant’s potential as a fuel crop.

They will discuss their research at the Delta Research Center Field Day, Sept. 2.

“In Africa, we can grow sweet sorghum twice a year, but here in America, you can grow it just once,” said Holou, who is originally from the African nation of Benin. “It’s a big benefit we have in Africa to get two yields.”

“Here in southeast Missouri, we may plant corn at the end of March or early April,” Stevens said. “With sweet sorghum, we usually have to wait until early May to plant.”

Stevens has planted five sweet sorghum varieties on about 10 acres at different seasonal timings to test which has more natural cold-tolerance. Once the plants mature, Holou measures the sugar content in their stems. The best-performing varieties may be candidates for efforts to genetically engineer a crop better suited to Missouri.

“If we can take genes from the cold-tolerant variety and put them into a variety that produces more sugar, we’ll get the best of both worlds,” Stevens said.

A more cold-tolerant, early-maturing hybrid could increase ethanol yields, he said. “If we can harvest earlier, it will grow back again and we could get two harvests instead of one.”

Making sweet sorghum a viable fuel crop would also benefit farming and conservation. “Sweet sorghum can be grown in areas where corn doesn’t grow very well right now,” Stevens said. “It’s another crop option that’s versatile and will keep performing in situations where corn won’t.”

Lower nitrogen needs could reduce runoff into streams. The plant is also carbon-neutral, Holou said. “It removes almost the same amount of carbon dioxide from the atmosphere while growing that is emitted during ethanol production.”

The field day will feature four tours covering cotton and corn; soybean; pest control; and energy and agriculture, during which Stevens will discuss his work with sweet sorghum.

For more information about the field day, call the Delta Center at (573) 379-5431.